David Humphreys played 72 times for Ireland and scored 560 points for his country.

A talented fly half with an excellent boot Humphreys made his international debut against France on 17 February 1996 while also having a distinguished career with Ulster, leading them to European glory in 1999.

Over time Ronan O'Gara rose to prominence and he eventually lost his place in the side to the Munsterman. He also captained Ireland in O'Gara's absence with the Lions in 2005 Japan. He came on as a substitute against New Zealand in November 2005, and did the same against Australia the following week. Humphreys captained Ireland for the fifth time in the November 2005 win against Romania.

He announced his retirement from international rugby after being an unused replacement throughout the 2006 Six Nations campaign.

He cemented his reputation for last-ditch heroics in the final match of the 2005-6 season. Ulster had gone into the final week of competition narrowly leading the Celtic League, but a decisive win for Leinster away to Edinburgh concluded during the final minutes of Ulster's final match, against the Ospreys in South Wales. With Ulster two points behind with just four minutes to go and the Ospreys dominating territorially, it looked like the cup would go to Dublin. Humphreys, however, kicked a last minute 40 metre drop goal to clinch the game and the league for Ulster.

He played his last ever match for Ulster against Cardiff Blues on 9 May 2008. He lead the team onto the pitch to a standing ovation from the Ravenhill crowd. He was substituted off after eight minutes with a bad limp, again to a standing ovation from the Ulster supporters as well as the Cardiff staff